This subproject is one of many research subprojects utilizing the resources provided by a Center grant funded by NIH/NCRR. The subproject and investigator (PI) may have received primary funding from another NIH source, and thus could be represented in other CRISP entries. The institution listed is for the Center, which is not necessarily the institution for the investigator. The nucleotide sugar UDP-galactose is essential for the biosynthesis of the main surface glycoconjugates of the human parasite Leishmania major. It is synthesized de novo by epimerization of UDP-glucose and by an undefined salvage pathway. Activation of galactose taken up from the environment typically involves a galactokinase and UDP-glucose-hexose-1-phosphate uridylyltransferase according to the Leloir pathway. Since both the de novo and Leloir pathways requires UDP-Glucose, the UDP-glucose pyrophosphorylase (UGP) catalyzing activation of glucose-1 phosphate to UDP-glucose was expected to control Leishmania glycocalyx formation.